Estudos da interação da Rosa de Bengala com a proteína Albumina do Soro Humano (HSA) sob aspectos experimentais e teóricos na caracterização dos sítios de ligação.
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Data
2021-11-19
Autores
Yoguim, Maurício Ikeda
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Universidade Estadual Paulista (Unesp)
Resumo
O corante Rosa de Bengala (RB) é um xanteno que possui algumas propriedades interessantes, como converter fotocatalíticamente moléculas de oxigênio para o estado singlete (1O2), e alterar a sua coloração de acordo com o valor de pH do meio. A compreensão da interação entre esse corante à macromoléculas biológicas é muito importante, porque estes estudos permitem compreender a formação de complexos como a proposição de mecanismos de interação e reação, estudos de reconhecimento à nível atômico e molecular dos sítios de ligação e a identificação das interações determinantes no processo de sua formação. A proteína escolhida para esse estudo foi a albumina do soro humano (HSA), que possui 9 sítios ativos para ácidos graxos (FA), ou 3 sítios de Sudlow, na qual é responsável por carrear compostos endógenos e exógenos para todo o organismo humano. Com os experimentos de Job´s Plot foi possível determinar que 6 estruturas do corante estão interagindo à estrutura da proteína, e estes possuem um valor médio de 3,90 ± 0,08 x 105 M-1 (constante de associação). Como o corante se interage à estrutura da proteína, averigou quais são os sítios ativos que o corante teve maior afinidade, desse modo, realizou tanto os experimentos laboratoriais (competição de sítios), como teóricos (docking molecular). Para os resultados experimentais foram observados que o RB possui afinidades aos sítios Sudlow I (IIA), FA1 (IB) e FA6 (IIB), e não ao sítio Sudlow II (IIIA). Com os estudos de docking molecular foram comprovados os mesmos resultados obtidos experimentalmente, e ainda foi possível identificar uma possível região preferencial ao sítio FA6. Os estudos termodinâmicos auxiliaram a compreender melhor a formação desse complexo, desse modo tem-se um ∆H>0 (endotérmico), ∆S>0 (grau de desordem mínimo) e ∆G<0 (reversível e espontâneo). Foi averiguado também que a formação do complexo apresentou um comportamento semelhante do RB nos meios caráter menos polares. Percebeu também que o corante interage com a proteína mesmo em situação onde há a deformação estrutural protéica, ocasionado por alguma patologia como Alzheimer, Diabetes e parkinson.
The Rose Bengal (RB) dye is a xanthene that has some very interesting properties, such as photocatalytically converting oxygen molecules to the singlet state (1O2), and also changing its color according to the pH value of the medium. Understanding the interaction between this dye and biological macromolecules, for example, is very important, as these studies allow us to understand the formation of complexes such as the preposition of interaction and reaction mechanisms, recognition studies at the atomic and molecular level of binding sites, and the identification of the determinant interactions in the process of its formation. The protein chosen for this study was human serum albumin (HSA), which has 9 active sites for fatty acids (FA), or 3 Sudlow sites, which is responsible for carrying endogenous and exogenous compounds to the entire human body. With the Job's Plot experiments it was possible to determine that 6 dye structures are interacting with the protein structure, and these have a mean value of 3.90 ± 0.08 x 105 M-1 (association constant). As the dye interacts with the protein structure, it investigated which active sites the dye had the greatest affinity, thus, it carried out both laboratory (site competition) and theoretical (molecular docking) experiments. For the experimental results, it was observed that RB has affinities to the Sudlow I (IIA), FA1 (IB) and FA6 (IIB) sites, and not to the Sudlow II (IIIA) site. With the molecular docking studies, the same results obtained experimentally were proven, and it was still possible to identify a possible preferential region to the FA6 site. Thermodynamic studies helped to better understand the formation of this complex, thus having a ∆H>0 (endothermic), ∆S>0 (minimum degree of disorder) and ∆G<0 (reversible and spontaneous). It was also verified that the formation of the complex presented a similar behavior to the RB in the less polar character media. He also noticed that the dye interacts with the protein even in a situation where there is structural protein deformation, caused by some pathology such as Alzheimer's, Diabetes and Parkinson's.
The Rose Bengal (RB) dye is a xanthene that has some very interesting properties, such as photocatalytically converting oxygen molecules to the singlet state (1O2), and also changing its color according to the pH value of the medium. Understanding the interaction between this dye and biological macromolecules, for example, is very important, as these studies allow us to understand the formation of complexes such as the preposition of interaction and reaction mechanisms, recognition studies at the atomic and molecular level of binding sites, and the identification of the determinant interactions in the process of its formation. The protein chosen for this study was human serum albumin (HSA), which has 9 active sites for fatty acids (FA), or 3 Sudlow sites, which is responsible for carrying endogenous and exogenous compounds to the entire human body. With the Job's Plot experiments it was possible to determine that 6 dye structures are interacting with the protein structure, and these have a mean value of 3.90 ± 0.08 x 105 M-1 (association constant). As the dye interacts with the protein structure, it investigated which active sites the dye had the greatest affinity, thus, it carried out both laboratory (site competition) and theoretical (molecular docking) experiments. For the experimental results, it was observed that RB has affinities to the Sudlow I (IIA), FA1 (IB) and FA6 (IIB) sites, and not to the Sudlow II (IIIA) site. With the molecular docking studies, the same results obtained experimentally were proven, and it was still possible to identify a possible preferential region to the FA6 site. Thermodynamic studies helped to better understand the formation of this complex, thus having a ∆H>0 (endothermic), ∆S>0 (minimum degree of disorder) and ∆G<0 (reversible and spontaneous). It was also verified that the formation of the complex presented a similar behavior to the RB in the less polar character media. He also noticed that the dye interacts with the protein even in a situation where there is structural protein deformation, caused by some pathology such as Alzheimer's, Diabetes and Parkinson's.
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Palavras-chave
Rosa de Bengala, Albumina do Soro Humano, Espectro de ultra-violeta visível, Docking molecular, Rose Bengal, Human Serum Albumin, Ultraviolet-visible spectrum, Docking molecular